Thermostat



Oct. 12, 1943.

s. l. RUSSELL 2,331,425

THERMOSTAT Filed Sept. 6, 1941 @IRK/mob 6am zel [asell JA/4%] CLA/ank, /ikm v OQTTOmLS Patented Oct. l2, 1943 UNITED STATES PATENT OFFICE 3 Claims.

tial amount of the time of a skilled operator andi-A hence is a material factor in the cost of these l5 units.

An object of the invention is to provide a new and improved thermostat which is durable, compact and rigid in construction and comprises a small number oi' parts capable of being quickly 20 and easily assembled with a high degree of` accuracy by a novel method, whereby the thermostat may be manufactured for sale at a relatively low cost.

More particularly stated, it is an object of the invention to provide a new and improved thermostat of they above-mentioned general type, embodying a base for supporting a thermal-responsive bimetal element between insulating spacers, the various parts being provided with novel means for facilitating assembly thereof in accurate alinement prior to the permanent assembly thereof.

Other objects and advantages of the invention will become apparent as the following description proceeds, taken in connection with the accompanying drawing, in which:

Figure 1 is an exploded perspective view of the various elements of a thermostat embodying the features of the present invention prior to assembly thereof.

Fig. 2 is a transverse vertical sectional view through the assembled thermostat and taken substantially along the line 2 2 of Fig. 3.

Fig. 3 is a longitudinal vertical sectional view taken on the line 3 3 of Fig. 2.

Fig. 4 is a longitudinal vertical sectional view similar to Fig. 3, and showing a slightly modified form oi the invention.

The structure embodying the instant invention which has been selected for illustration is of a type particularly well adapted for use in apparatus wherein the thermostat is, of necessity, relatively small. Thermostats of this general type embody a plurality of parts such, for example, as flat insulating spacers and bimetal plates which, due to their small size, lare diilicult to assemble, aline and hold in alined position until they are permanently secured. Exact alinement,

(ci. 297-15) n mary importance in a control device of this nature to assure accuracy of function and permanency of a calibrated setting. Accordingly, it has heretofore been necessary to use great care and considerable skill in manipulating the parts to their desired positions. I have provided a. simple, yet eilective, means and method, requiring no particular care or dexterity, for assembling the parts accurately in alined relationship in which they are positively retained until finally secured in their permanent relation.

Referring more particularly `to Fig. 1 of the drawing, the illustrated embodiment of the invention has a base or frame I0 in the form of an elongated, U-shaped channel comprising the main supporting member of the thermostat. At one end of the channel frame the side walls project integrally upwardly to form ears II. In the present instance, the ears extend through approximately one-third of the length of the frame. Stamped or otherwise suitably formed in the base of the channel frame and within the area over which the ears II extend,rare a pair of substantially centrally located, longitudinally spaced projections I2 which extend upwardly within the channel. A thermal-responsive bimetal element I3, elongated in form and adapted to extend longitudinally and substantially centrally within the channel frame, is provided with a pair of apertures I4 substantially corresponding in location to the projections I2 formed in the base.

lThe thermal element I3 is rigidly supported, cantilever fashion, within the end of the channel member occupied byV the projections and in spaced, insulated relation .thereto to extend freely for thermal-responsive movementl over the remaining length of the channel frame. end, a pair of insulating spacers I5 and I6, which in the present instance are approximately the same length as the ears II, are adapted for assembly on the opposite sides of the bimetal element I3 to hold the latter in insulated and spaced relation with respect to the channel frame. The inner spacer I5 between the base of the channel and the bimetal element is stamped or otherwise suitably formed with a pair of recesses or indentations Il on its bottom or base engaging face, and with a pair of projections I8 on its upper or element-engagingl face. The indentations Il and projections I8 may be and preferably are formed simultaneously by offsetting or in effect extruding portions of the body ma- -terial laterally out of the plane of the body.

adjustment and security of assembly are of pri- U0 The recesses and projections are spaced and dimensioned for closely t'ting registration, respectively, with the projections I2 on the base of the channel and with the apertures I4 in the bimetal element I3 (as seen in Fig. 3). The spacer I6 is superimposed on the element I3 and the parts are clamped in position by bending 0r To this Vchanges in temperature.

overturningv the ears II, as seen best in Fig. 2, to overlie the spacer I6 and clamp the parts in assembled relation.

Any suitable contact means may be provided at the remote or free end of the bimetal element I3 to make and break an electrical circuit as the strip iiexes back and forth in response to Thus, a suitable contact point I9 is secured in a customary manner to the free end of the bimetal element I3 for coaction with an opposed point 20 mounted on the end of an adjustable contact strip 2l. The strip is of resilient material and is suitably secured by such means as a rivet 22 to extend substantially centrally of the channel frame in generally parallel relation with the` bimetal element.

A set screw 23 screw-threaded in the base of the channel opposite to the free end of the strip 2I engages the strip for adjustment and calibration of the device. Since the contact strip 2| is resilient the set screw 23 will always be urged in one direction, thereby eliminating end play and consequent inaccuracy in the thermal control.

In the alternative embodiment illustrated in Fig. 4, the inner insulating spacer I e is provided with projections I8 which are somewhat longer than the projections I8 formed on the spacer I5 Vto extend through and beyond the apertures I4 in the bimetal element I3. In this embodiment receiving apertures 26 are formed in the outer spacer I6, The apertures 26 and Id and the cooperating elongated projections I-8a provide means for accurately alining the outer spacer I 6e, the bimetal element I3, the bottom spacer I5 and channel base I0. Instead of using a differently formed outer spacer I6 a second spacerY I5a may be employed. In this case the indentations I'I in the outer spacer coacts with the projections I8a on the inner spacer in determining alinement. The projection I8a on the ent arrangement the simple act of stacking the parts one upon the other is eflective denitely' adapted for thermostats which are quite small since it eliminates the diiculties heretofore encountered in assembling with speed and accuracy the small parts of the unit.

I claim as my invention:

1. In a thermostat of the character described,

Y the combination of an elongated channel-shaped frame having at one end a pair of ears, a pair oi.' spaced projections stamped inwardly from the base of said frame at said one end, an elongated insulating spacer superimposed on said base in fiat face-to-face registration therewith and having a pair of complementary indentations in its registered face engaging said projections, said spacer having a pair of spaced projections formed on its oposite face, an elongated bimetal element superimposed on said spacer in flat faceto-face registration therewith and having a pair of apertures engaged by said projections on said spacer, said element extending longitudinally of said frame and being free at its other end for thermal-responsive movement, and a second spacer superimposed on said bimetal element, said ears being overturned to engage the outer face of said second spacer and secure the superimposed parts together and to the frame.

2. In a thermostat of the character described.

40 the combination of an elongated base having a outer spacer will in this arrangement be compressed when the ears I I are overturned to increase the security of the assembly.

The preferred method employed in making th thermostat of the instant invention contemplates the following steps: As the channel frame III is formed with the ears I I in the respective planes of the side walls, thc two stamped indentations I2 in the base of the frame are also formed. The resilient member,` 2|,is then secured to the base. When the inner or bottom spacer I5 is cut to size, it is also stamped to Drovide the two indentations I1 on one.` face and the two projections I8 (or Ilia) on the other face. In the alternative embodiment illustrated in Fig. 4, the spacer I6B may be provided during its formation with the apertures 26. The bimetal element I3, during its forming operation, is provided with the apertures I4.

To assemble the parts, the-inner spacer I5 is placed on the base of the frame I0 with the indentations Il'engaging the projections I 2. The element I3 is then easily and quickly located in properly spaced relation to the frame by causing the apertures Id to register with the projections i8. The outer spacer (I6 or II5a depending on the length of the projections I8 or I8a) is then placed on the bimetal element I3 t-o complete this stack of three parts. During the course of such assembly operation, the necessity for carefully alining and holding the parts alined is obviated by the provision of the intertting indentations, apertures and projections. With the presprojection formed near one end thereof, a bimetal strip having an aperture formed therethrough near one end thereof, an elongated insulating spacer between said element and said base and having a substantial at face-to-face contact with said element and said base along its opposite sides respectively, said spacer having a projection on one face and an indentation on the other face for snugV engagement respectively with said aperture in said element and said projection on said base, a second insulating spacer on the opposite side of said element, and a pair of ears integral with said base and bent lover said second spacer to hold said spacers and said element in assembled relation.

3. In a thermostat of the character described, the combination of an elongated frame having projections formed therein adjacent one end thereof, an elongated bimetal element mounted to extend longitudinally of said frame and having apertures formed therein near one end thereof, an elongated insulating spacer between said element and said frame and having at faceto face contact with said frame for a substantial distance and having'indentations formed in one side thereof and projectionsformed on its other side adapted respectively for registration with the projections in said base and for extension through the apertures in said element, and a second insulating spacer superimposed on the other side of said element and having means cooperating with the projections extending through said apertures for locating said second spacer with respect to said element.

SAMUEL I. RUSSELL. 

